Opportunity
Modern buildings account for over 40% of global primary energy consumption, largely due to the widespread use of glass facades with high solar transmittance. Traditional windows lack dynamic solar regulation, leading to significant thermal loss/gain and contributing to urban greenhouse gas emissions. While thermochromic smart windows, particularly those using metal halide perovskites, offer a solution, they face critical challenges. These include degradation under high humidity, high optical haze formation, and lead leakage, which threaten environmental and public health. Existing solutions, such as sealing perovskites or using protective layers, often compromise optical performance or fail to provide long-term durability. This patent addresses these issues by introducing a novel composite material that enhances durability, optical performance, and environmental safety.
Technology
The patent presents a three-layer composite material:
1. Thermochromic Perovskite Layer: Composed of halide-based perovskites (e.g., (CH3NH3)4PbI6−yCly·2H2O), this layer reversibly changes color with temperature via hydration-dehydration reactions.
2. Anti-Reflective Layer: A polymer (e.g., perhydropolysilazane, PHPS) deposited atop the perovskite, smoothing surface roughness and reducing light scattering. Its refractive index (≈1.55) bridges air (n=1.0) and perovskite (n≈2.0), enhancing transparency.
3. Superhydrophobic Layer: A fluorinated silica nanoparticle coating repels liquid water while allowing controlled water vapor diffusion for thermochromic activation.
Advantages
- Enhanced Durability: 45-day stability with 37× slower decay than conventional perovskites.
- High Optical Performance: 83.4% visible transmittance (cold state) and 24.4% solar modulation (ΔTsol).
- Low Haze: <30% haze="" vs.="" 90%="" in="" untreated="" perovskites,="" enabling="" clear="">
- Environmental Safety: Reduces lead leakage by 66× compared to unprotected perovskites.
- Scalable Fabrication: All layers are applied via solution-based methods (spin-coating, spraying).
Applications
- Smart Windows: Dynamic solar regulation for energy-efficient buildings.
- Flexible Films: Compatible with PET substrates for retrofit applications.
- Automotive Glass: Thermal management for vehicle interiors.
- Optoelectronic Devices: Light-modulating components for displays or sensors.
